GDI엔진의 밸브리프트 변화에 따른 연소실내 흡기유동 및 연료분포에 대한 수치 해석적 연구 = A Numerical Study in the In-cylinder Flow and Fuel Distribution with the Change of Intake Valve Life in a GDI Engine

다국어 초록 (Multilingual Abstract)

While variable value actuation or variable valve lift (VVL) is used increasingly in spark ignition (SI) engines to improve the volumetric efficiency or to reduce the pumping losses, it is necessary to understand the impact of variable value lift and timing on the in-cylinder gas motions and mixing processes. In this paper, characteristics of the in-cylinder flow and fuel distribution for various value lifts (4, 6, 8, 10mm) were simulated in a GDI engine. It is expected that the investigation will be helpful in understanding and improving GDI combustion when a VVL system is used. The CFD results showed that a increased value lift could significantly enhance the mixture and in-cylinder tumble motion because of the accelerated air flow. Also, it can be found that the fuel distribution is more affected by earlier injection (during intake process) than that of later injection (end of compression). These may contribute to an improvement in the air-fuel mixing but also to an optimization of intake and exhaust system.